Electric couplings



Feb. 1966 E. c. BUCKLAND ELECTRIC COUPLINGS 2 Sheets-Sheet 1 Filed April 19, 1962 3 9 on E lNvENTok ERNEST [A/FFo/w BI/t/(Lfl/VD M M W ATTORNEYS Fe b. 8, 1966 g. uc L 3,234,500

ELECTRIC COUPLINGS Filed April 19, 1962 2 Sheets-Sheet 2 INV ENTOR NEST 61 IFFORD Bur/(Law ATTORNEYS.

United States Patent ELECTRIC COUPLINGS Ernest C. Buckland, Wrayshury, England, assignor to M. B. Metals Limited Filed Apr. 19, 1962, Ser. No. 188,657 Claims priority, application Great Britain, Apr. 20, 1961,

Claims. (Cl. 339182) This invention relates to electrical connectors of the separable kind, where electrical connection is established when two members are offered up one to the other. It is convenient to refer to the two members as plug member and socket member, and to the connector as a plug and socket connector, though it is not thereby to be inferred that one member is a simple plug and the other is a simple socket.

The present invention is more particularly concerned with the provision of a plug and socket connector suitable for use in exceptionally arduous circumstances, and specifically those existing in nuclear reactors.

In a nuclear reactor it is necessary to monitor the temperature of the fuel elements; a suitable device responding to the temperature of the element is a thermocouple. As a matter of practical convenience it is very desirable that a separable electric coupling to the thermocouple be provided but the working requirements of such a coupling are so difficult that so far as we are aware no coupling having adequate durability and reliability has been available. For example, such a coupling must be capable of operating continuously at a temperature of several hundred degrees centigrade, in an atmosphere at high pressure, and must be made of materials compatible with the fuel element casing. It is of the utmost importance that the electrical connection should be reliable at all times, over long periods when it is not possible to move or renew the contact-making surfaces. Finally, it is desirable that the engagement of the members should be effected by a simple, direct, relative movement.

The present invention concerns a plug and socket connector which can be made in a form suited to this service.

Broadly, the invention consists of an electrical connector comprising plug and socket members adapted to be engaged by approximately linear relative movement, and co-operating contact pairs in said members, each co-operating pair of contacts including a first contact on one of said members presenting a cylindrical contact surface and a second contact on the other of said members in the form of a wire or the like shaped to have a non-cylindrical contact surface for engaging the said cylindrical surface locally at a plurality of points, the second contact having radial resiliency at those points.

Other features and advantages of the present invention will appear from the following description of embodiments thereof, given by way of example, in conjunction with the accompanying drawings, in which:

FIGURE 1 is a sectional view through the socket mem ber of a coupling, suitable for the service mentioned above;

FIGURE 2 is a section through the cooperating plug member;

FIGURE 3 is an end view of the socket member contacts;

FIGURE 4 is a part-sectional View of the socket mem-' ber of a second form of coupling in accordance with the invention, and

FIGURE 5 is a part-sectional exploded view of a plug member co-operating with the socket member of FIG URE 4.

' The two parts of the coupling shown in FIGURES 1 and 2 have some features in common, but the socket ice member shown in FIGURE 1 will be first described. This includes a body 10, suitably of stainless steel, having at its forward end an entry opening at 10a and 10b. Mounted within the body is a contact assembly which comprises, at one end of the body, a cylindrical cup 11, in which are secured by a brazing process two sleeves, 12 and 13, of ceramic material. This brazing connection results in a rigid fixing and gas-tight seal between the body of the ceramic sleeve 12, 13. The method by which ceramic material can be brazed to the cup in this way is a known one. Two contacts, 14 and 15, are mounted respectively in the sleeves 12 and 13. These contacts are in the nature of thick wires, the shape of which will be described further hereinafter. The wires are composed of a highly durable material, resistant to corrosion at high temperature, of high electrical conductivity and capable of retaining mechanical properties at high tempreature, and compatible with the material used for a fuel element casing. A suitable composition of materials for the contacts is a base material alloy available under the trademark Nimonic, with a surface coating of platmum-ruthenium.

The contact wires are mounted on and sealed to the sleeves 12, 13 and for this purpose there is used a pair of ferrules 16, 17. The ferrules have cap portions 16a, 17a that fit over the ends of sleeves 12, 13 respectively and are brazed to them, and reduced portions 16b, 17b into which the contact wires fit and also are brazed. In this way the contact wires are firmly supported from cup 11, but insulated from it, and the interior of the cup is sealed at the entry points.

The forward ends of the contacts 14 and 15 are shaped to provide a durable contact with the co-operating plug member, shown in FIGURE 2, of which the contact-making portion is of generally cylindrical configuration; the plug member is described in more detail hereinafter. To co-operate with the cylindrical part of the plug the contacts'14 are first bent outwardly as at 14a, 15a, and are then shaped so that viewed endwise they are of square shape, as shown in FIGURE 3, with the inner diameter of the square being slightly less than the external diameter of the co-operating part of the plug. Ceramic rings 20, 21, and 22 are provided between and around the contactmaking parts of contacts 14 and 15 in order to limit their movement and to provide adequate high temperature insulation between these portions and the metal body 10.. As will be seen, ring 22 is a. plain annulus; ring 21 is an annulus with a recess in end face so that when in contact with the adjacent face of ring 22 there is defined in recess to receive contact 15. This recess prevents excessive movement of contact 15 both longitudinally and radially. Ring 21 also has a slot to accommodate the longitudinally extending part of the contact 15.

Ring 20 is of the same general shape as ring 21, so as to form, with ring 21, a recess to receive contact 14, and has a slot, indicated at Zlla for the longitudinal part of contact 14 and a similar slot for the longitudinal part of contact 15. The rings are held in position against a shoulder ltlc on the end of the body by sleeve 18, in turn held by cup member 11, brazed to body 10.

It is necessary that an adequate gas-tight connection be provided at the rear ends of contacts 14 and 15. This is provided by an end closure 23 for the cup 11, welded into position, with an insulating ring 24 of ceramic, within the cup, serving as a spacer. Closure 23 includes a central boss 25 to which a stainless steel tube 26 extends to the thermocouple element. The wires 27, 28 of the thermocouple extend, with suitable insulation, through tube 25 and are brazed or welded to the projecting ends of the contacts 14 and 15. The socket member described is intended to be secured to the end of a fuel element and for this purpose a coupling ring 30 is mounted on the exterior of the body, the body being formed with a securing flange 31.

The plug member which co-operates with the socket shown in FIGURE 1 includes a body 40 of stainless steel having at its forward end a cylindrical extension 41, of an internal diameter to enable it to pass over the end of the socket member body 10. The plug portion of this contact is built up from a series of rings 42, 43 and 44, between which are clamped two discs 45 and 46 of platinum. The plug assembly is attached to a backing member 47, the whole assembly being held together by screws 49 passing through a front disc 48 and threaded into the backing member 47. The exposed edges of the discs 45 and 46 form contact members proper, and connection to these is effected by rods 50, 51, passing through the plug assembly and brazed to the respective disc. Where they emerge through the backing member 47, the rods are surrounded by short sleeves 52, 53 of ceramic. It will be understood that the ceramic rings. 43 and 42, and the disc are formed with openings for the passage of rods 50, 51, to hold these rods in the appropriate positions and out of electrical contact with each other.

The terminal arrangement to the rods 50, 51 is the same as that adopted for the contacts 14 and in the body, and comprises a cup member 55 brazed to ceramic sleeves 56, 57, similar to sleeves 12 and 13, ferrules 53, 59 brazed to the rods 50, 51 and to the sleeves 56, 57. A slightly different exit connection from body it is made, a disc 61 being brazed to the boss 62 on the cup 55 of the plug, and also to the interior of the body 40. Connection is made externally through stainless steel tube 63.

In manufacture, a sub-assembly including the contact discs, the spacing rings and cup 55, with an interposed ceramic spacer 64, is first made. of the contact disc-ceramic insulation is ground accurately cylindrical and concentric with the cylindrical cup 55. The sub-assembly is then inserted in the body until the end member 47 abuts the shoulder at the end of the bore in the body, and then disc 61 is inserted and brazed in position.

When the plug and socket members are offered up together the surfaces first engaging are tapered ensuring self-alignment of the members. Also, as will be seen from FIGURE 2, the leading edge of disc 48 is also tapered and this facilitates entry of the plug into the socket members.

The shape adopted for contacts 14 and 15 in relation to contacts 45, 46 causes localised engagement between these contacts, and hence good contact pressure for a given insertion force. The square socket and circular plug are not the only shapes that will give these advantages; other relative shapes will serve, including shapes with three ormore than four localised contact areas. A cylindrical plug is preferred, for ease of manufacture.

The invention can be applied to other than a two-way connector, and a ten-way connector is shown in FIGURES 4 and 5. The construction adopted resembles in various respects that adopted for the two-way arrangement and will therefore be more briefly described.

In the socketmember of FIGURE '4 the body 70 receives at one end a cup member 71, brazed to it. Assembled between the cup member and the end face of the bore in the body is a stack of ceramic insulators 72. The insulators provide recesses for contact members 73, the longitudinally extending parts of the members 73 passing through registering openings in the insulators, and being then sealed to the cup member 71 by ceramic sleeves 7'4 and ferrules 75. T he end of the body is closed by a disc 76 having a cylindrical flange 77 that fits onto a boss 78 on cup member 71, the two parts being pinned at $0. Lead out-tubes 88 are brazed into disc 76, the conductors of which are resistance welded to the appropriate conductors 73. When these connectionshave been made a sleeve is fitted over the exposed parts and The external surface brazed at 81 to the cup member 71 and at 82 to disc 76. After baking-out a grub screw 83 is inserted in a threaded hole in the sleeve and the end welded over to seal the interior of the sleeve. If desired, the sleeve and ferrule type of exit connection can be used for some of the connections as at 84, 85, on a disc 86 welded to an external flange 87 of the disc 7 6.

The corresponding plug is shown in FIGURE 5. A body 99 has a stack of ceramic discs 91 and contact disc 92 assembled upon it, using clamping screws as before. Ceramic sleeves 93 and ferrules 94 are sealed in a cup member 95 fitting within the body 90 and are used to make connection to the connecting wires 96 to contacts 92; the individual parts of wires 96 exposed within the body carry insulating sleeves 98. Lead out tubes 99 are brazed to a closure 100, pinned at 101 to a boss 102 on cup member 95. Sealing is completed by means of a shaped sleeve 193 welded to the cup member at 104 and to the closure member at 105. A mounting gland 166 can fit on the end of the assembly.

The two constructions of connector described are very satisfactory in use in the service; it will be appreciated that the advantages of reliable connection and durability can be of value in other applications.

What I claim is:

1. An electrical connector assembly for use at high temperatures and in arduous service conditions, for establishing electrical connection between an electrical device and sheathed conductor means, said conductor means including an outer continuous impermeable metallic sheath and at least one conductor within said sheath, said connector comprising a socket member and a plug including a cylindrical pole member slidably insertable into the socket to a predetermineddepth therein, said socket member comprising a stack of annular insulating elements shaped to define a cylindrical inner peripheral surface of said socket member serving as a receptacle for said pole member, said stack of elements defining also a plurality of peripheral grooves in said peripheral surface, a plurality of electrical contact elements disposed respectively in said grooves, each said contact element being fitted in the respective groove so as to be permitted a degree of displacement in the direction radial of said cylindrical surface but limited against movement in the direction axial of said surface, each said contact element comprising an elongated member shaped to present an annular portion lodged in the respective groove, said annular portion being radially resilient and having a non-circular in ner periphery, and a further integral adjacent portion extending in a direction along the length of said groove, said socket member including spaced walls to define a sealed chamber, said walls having therein openingsfor the entry of said sheath conductor means and for the said further portions of said contact elements, sealing means for sealing the said sheath andthe said further portions to the opening through which they respectively pass, said pole member including a plurality of spaced insulated ring contact elements exposed on a cylindrical insertable surface of the pole member, the lengthwise spacing of the contact elements in said members being such that upon insertion of the pole member into the socket member to said predetermined depth the contact elements on said members are in contact-making engagement With each other ata plurality of discrete spaced circumferential points.

2. An electrical connectorin accordance withclaim 1, wherein the contact elements having the unround peripheral outline include 'a plurality of approximately straight portions adjacent ones of which are atan angle to each other.

3. An electrical connector in accordance with claim 1 wherein the contact elements in the pole member of the plug have said cylindrical peripheral outline and the contact elements in said socket member have said unround peripheral outline, and wherein said socket member comprises an outer casing, the contact elements and the insulation elements of the socket member being stacked in superimposition in said casing to form therein a lining defining a generally cylindrical outline from which the respective contact elements protrude radially inward for contact engagement with the contact elements in said pole member.

4. An electrical connector in accordance with claim 3, wherein said Contact elements in the pole member each comprise a generally cylindrical conductive body arranged in the plane transverse to the axis of the cylindri- 521T surface, assembled with interposed insulation elements.

5. An electrical connector in accordance with claim 4, and comprising connections to said contact elements in the pole member lying in a direction along the length of the axis of the cylindrical surface, towards one end of the assembly.

References Cited by the Examiner UNITED STATES PATENTS 1,901,040 3/1933 Peroni et a1 339182 X 2,968,020 1/1961 Barnhart 339-94 X 2,972,125 2/1961 Temple et al. 33961 2,986,613 5/1961 Figueira 339-94 X FOREIGN PATENTS 227,696 4/ 1960 Australia. 1,036,971 8/1958 Germany.

578,576 7/ 1946 Great Britain.

JOSEPH D. SEERS, Primary Examiner.

W. D. MILLER, Assistant Examiner. 

1. AN ELECTRICAL CONNECTOR ASSEMBLY FOR USE AT HIGH TEMPERATURES AND IN ARDUOUS SERVICE CONDITIONS, FOR ESTABLISHING ELECTRICAL CONNECTION BETWEEN AND ELECTRICAL DEVICE AND SHEATHED CONDUCTOR MEANS, SAID CONDUCTOR MEANS INCLUDING AN OUTER CONTINUOUS IMPERMEABLE METALLIC SHEATH AND AT LEAST ONE CONDUCTOR WITHIN SAID SHEATH, SAID CONNECTOR COMPRISING A SOCKET MEMBER AND A PLUG INCLUDING A CYLINDRICAL POLE MEMBER SLIDABLY INSERTABLE INTO THE SOCKET TO A PREDETERMINED DEPTH THEREIN, SAID SOCKET MEMBER COMPRISING A STACK OF ANNULAR INSULATING ELEMENTS SHAPED TO DEFINE A CYLINDRICAL INNER PERIPHERAL SURFACE OF SAID SOCKET MEMBER SERVING AS A RECEPTACLE FOR SAID POLE MEMBER, SAID STACK OF ELEMENTS DEFINING ALSO A PLURALITY OF PERIPHERAL GROOVES IN SAID PERIPHERAL SURFACE, A PLURALITY OF ELECTRICAL CONTACT ELEMENTS DISPOSED RESPECTIVELY IN SAID GROOVES, EACH SAID CONTACT ELEMENT BEING FITTED IN THE RESPECTIVE GROOVE SO AS TO BE PERMITTED A DEGREE OF DISPLACEMENT IN THE DIRECTION RADIAL OF SAID CYLINDRICAL SURFACE BUT LIMITED AGAINST MOVEMENT IN THE DIRECTION AXIAL OF SAID SURFACE, EACH SAID CONTACT ELEMENT COMPRISING AN ELONGATED MEMBER SHAPED TO PRESENT AN ANNULAR PORTION LODGED IN THE RESPECTIVE GROOVE, SAID ANNULAR PORTION BEING RADIALLY RESILIENT AND HAVING A NON-CIRCULAR IN- 